I've typically sought out mostly friends in the past for mine. Though before I moved to California, I had a really good writing group I found on Meetup that was local that was great for helping too. I'd check to see if your area is on their website and if there are any groups nearby.
As an additional resource, I'd check out this channel for ideas: https://www.youtube.com/channel/UCS_fcv9kBpDN4WWrfcbCrgw/videos (though be warned, she does swear a lot and is often blunt)
GoodReads should have some beta groups on there. A quick search brought up this one, which looks active: https://www.goodreads.com/group/show/50920-beta-reader-group Though no doubt there are others.
You might also be able to do trades with other authors looking for betas. You beta theirs and they beta yours.
The thing with betas is that you'll want several going at once, since some of them will drop off at some point in the process. So don't feel bad if you have your book out with 5-10+ people at one time. (As in, don't just stop once you get one person interested in beta reading. Keep asking around, jic.)
I get that it's frustrating though. My most recent book I'm working on has had basically all of my betas drop for various reasons. Finding new ones can be tough, but hopefully you can get some. <3